Octree octree = PhysicsUtilities.ExtractOctree(model);
octree.BuildOctree();

Body body = new RigidBody(new TriangleMeshShape(octree));
body.IsStatic = true;

CollisionSystem collisionSystem = new CollisionSystemSAP();
collisionSystem.CollisionDetected += OnCollisionDetected;

World world = new World(collisionSystem);